The flexibility of nylon monofilament fishing nets in low-temperature environments is a key indicator of their suitability for operation in cold waters. As a polymer material, the molecular chain structure of nylon monofilaments undergoes significant changes at low temperatures, directly affecting the flexibility and performance of the fishing net. This change stems from a reduction in molecular chain mobility—when the ambient temperature approaches or falls below the glass transition temperature of nylon, the rotational and sliding abilities of the molecular chains weaken, and the material gradually transitions from a highly elastic state to a glassy state, leading to decreased flexibility and increased brittleness. Although nylon monofilaments possess excellent elasticity and abrasion resistance at room temperature, low temperatures weaken the intermolecular forces, making the fishing net more prone to breakage or permanent deformation under stress.
The limitation of low temperatures on the flexibility of nylon monofilament fishing nets is primarily reflected in the increased rigidity of the molecular chains. At room temperature, nylon molecular chains are in a random coiled state, able to absorb external impacts through the movement of chain segments, thus maintaining flexibility. However, as the temperature decreases, the thermal energy of the molecular chains weakens, chain segment movement is hindered, and the material gradually becomes stiff. This increased rigidity leads to greater internal stress in the fishing net when folded, stretched, or bent, increasing the risk of molecular chain breakage. For example, in deep-sea trawls, the net frequently withstands tension and friction; insufficient flexibility can cause the mesh to break due to stress concentration, affecting fishing efficiency. Furthermore, low temperatures cause dimensional shrinkage of the nylon monofilaments, further limiting flexibility. Nylon materials exhibit thermal shrinkage; as ambient temperature drops, the spacing between molecular chains narrows, causing the overall size of the fishing net to shrink.
This shrinkage not only alters the uniformity of the mesh but can also reduce the fit between the net and components such as frames and floats, increasing operational difficulty. For instance, in fast-flowing reservoir environments, excessive deformation due to low-temperature shrinkage may prevent effective fish interception, potentially leading to fish escape. Simultaneously, dimensional shrinkage exacerbates uneven stress distribution within the net, making localized areas more prone to fatigue fracture.
Frozen water in low-temperature environments is also a significant factor limiting the flexibility of nylon monofilament fishing nets. Although nylon monofilaments possess some hydrophobicity, moisture can still be absorbed by the surface of fishing nets in humid or high-salinity waters. When temperatures drop below freezing, this absorbed moisture freezes and expands, compressing the internal structure of the net. This ice crystal expansion not only disrupts the molecular chain arrangement but can also trigger the propagation of microcracks, leading to a significant decrease in the net's flexibility. For example, in sea areas like the northern Bohai Sea where surface water temperatures approach freezing in winter, prolonged exposure of fishing nets to low temperatures can drastically reduce their tensile strength and elongation at break, increasing operational risks.
To address the limitations of low temperatures on flexibility, the production process of nylon monofilament fishing nets needs targeted optimization. For instance, adding plasticizers or blending modifiers can lower the glass transition temperature of nylon, slowing down the rigidification of molecular chains at low temperatures. Simultaneously, using heat-setting processes to eliminate nodal stress generated during net weaving can improve mesh uniformity and resistance to deformation. Furthermore, selecting polymer materials with lower embrittlement temperatures (such as PTT) as alternatives can also maintain good flexibility in extreme low-temperature environments. These process improvements significantly enhance the adaptability and durability of fishing nets in low-temperature environments.
In practical use, the low-temperature flexibility of nylon monofilament fishing nets is also affected by operating methods and maintenance conditions. For example, before low-temperature operations, preheating (such as immersion in warm water or using heating equipment) can raise the initial temperature of the net, reducing the rigidity of the molecular chains. After operations, any adhering substances (such as fish scales and algae) on the net surface should be cleaned promptly to prevent organic matter from accelerating material aging. Simultaneously, storing the net in a dry, dark environment can prevent embrittlement caused by the combined effects of low temperature and humidity. These maintenance measures can extend the service life of the fishing net and reduce the long-term impact of low temperatures on flexibility.
The flexibility of nylon monofilament fishing nets in low-temperature environments is constrained by multiple factors, including molecular chain structure, dimensional shrinkage, and water freezing. Through material modification, process optimization, and scientific maintenance, these constraints can be effectively mitigated, improving the performance of fishing nets in cold waters. For low-temperature applications such as deep-sea fishing and aquaculture in high-latitude regions, choosing a specially treated nylon monofilament fishing net is key to ensuring both fishing efficiency and operational safety.
